New member
Jun 8, 2008
I am installing a pool and I was wondering what is a safe weed killer for under the liner? I've heard of pure blue but I don't think you can get that in Canada. I've also heard about people using round up and I don't know how safe that would be with the liner. I searched and heard of people using salt, vinegar and bleach but do they or anything else last long term? I have removed all grass, and thought all the roots and set up the walls with the sand that is level.

I have been trying to use the old liner since I was given the pool but it appears to have shrunk too much so I bought a new one. But during my 3 failed attempts to get the liner to match up properly I have noticed weeds growing through the sand and it doesn't appear that being covered by the liner stopped them one bit and they continue to grow. The weeds look like a climbing weed vine thing. So currently I have the walls set up with sand and Styrofoam coving.



LifeTime Supporter
May 31, 2007
Rocklin, Ca
My understanding is that Round Up and similar products, which I use regularly, work by spraying directly on the plants. The plant then absorbs the poison killing it. These products also kill the roots. Some stubborn plants like crab grass is very difficult to kill and requires many applications of the stuff. The stuff works best with strong sunlight so I try to apply it in the morning.

I don't understand why you need to get behind the liner since this is only where the roots are.